4X18A’s driver is linear, not buck
Also, max achievable turbo brightness drops smoothly as the batteries drain so it makes sense that voltage sag is the cause.
Happy Birthday Simon Mao......Wishing you the biggest birthday celebration today, good health and more flashlights to build.
Happy Birthday Simon!
Have a great day, cheers!
Happy Birthday, Simon! 
Happy birthday Simon! Thanks for your continued interaction with us. It is greatly appreciated.
I didn’t know the regulator was linear, touché. Still, worst case is 4 - 6A draw per cell. Voltage sag may still be the culprit, but well within the cells’ capabilities. Only way to know for sure would be to test with different cells and compare I suppose.
About 70~80mV higher with 30Q at 5A at high SOC, not a big difference but it can help a bit.
More importantly the 180mV drop across the sense resistor doesn’t help.
With 30Qs and a more reasonable 50mV Vsense, 0.2V would be saved, that’s significant.
7135*4 is out of stock
Although today is not my birthday, I still want to thank you all. :partying_face:
There’s an interesting thing in there. China has a lunar calendar and a solar calendar. Actually my birthday is counted according to the lunar calendar. 
When will the 23.2*1.4mm ar-coated glass lens ,suitable for Convoy S21A S21B be available with the new green AR coating?
Some use new green coated lenses.
Excellent, I’ll add the lens to my order!
Simon, is there any chance of adding additional colors to the standard anodized aluminum S2+? It would be great to see a yellow one.
Yellow doesn’t look very flattering
Titanium alloy T4
Hey that’s my favorite color! 
I understand though if it’s not worth it to manufacture since there wont be enough demand.
Do you have an estimate of when the MAO version will be available?
Wow. That’s gorgeous! What else is coming in Ti?
He mentioned that it would be 3-4 weeks about 2 weeks ago. So hopefully 1-2 more weeks if there are no delays.
Oh that titanium looks beautiful! Better make plenty of those ahead of the Christmas gift season. 
Great looking!
Now we need S2+ and T3 in Titanium